Detect and set proper Content-Type for avatars

Detect proper avatar type to return instead of returning `image/*`, which is not valid.
go-pkgz · Sep 21, 2024 · 23da433 · 23da433
1 parent 458e57e
commit 23da433
Show file tree

Hide file tree

Showing 4 changed files with 46 additions and 16 deletions.
diff --git a/avatar/avatar.go b/avatar/avatar.go
@@ -23,6 +23,9 @@ import (
 	"github.com/go-pkgz/auth/token"
 )
 
+// http.sniffLen is 512 bytes which is how much we need to read to detect content type
+const sniffLen = 512
+
 // Proxy provides http handler for avatars from avatar.Store
 // On user login token will call Put and it will retrieve and save picture locally.
 type Proxy struct {
@@ -100,7 +103,6 @@ func (p *Proxy) load(url string, client *http.Client) (rc io.ReadCloser, err err
 
 // Handler returns token routes for given provider
 func (p *Proxy) Handler(w http.ResponseWriter, r *http.Request) {
-
 	if r.Method != "GET" {
 		w.WriteHeader(http.StatusMethodNotAllowed)
 	}
@@ -136,9 +138,21 @@ func (p *Proxy) Handler(w http.ResponseWriter, r *http.Request) {
 		}
 	}()
 
-	w.Header().Set("Content-Type", "image/*")
+	buf := make([]byte, sniffLen)
+	n, err := avReader.Read(buf)
+	if err != nil && err != io.EOF {
+		p.Logf("[WARN] can't read from avatar reader for %s, %s", avatarID, err)
+		rest.SendErrorJSON(w, r, p.L, http.StatusInternalServerError, err, "can't read avatar")
+		return
+	}
 	w.Header().Set("Content-Length", strconv.Itoa(size))
+	w.Header().Set("Content-Type", http.DetectContentType(buf))
 	w.WriteHeader(http.StatusOK)
+	if _, err = w.Write(buf[:n]); err != nil {
+		p.Logf("[WARN] can't write response to %s, %s", r.RemoteAddr, err)
+		return
+	}
+	// write the rest of response size if it's bigger than 512 bytes, or nothing as EOF would be sent right away then
 	if _, err = io.Copy(w, avReader); err != nil {
 		p.Logf("[WARN] can't send response to %s, %s", r.RemoteAddr, err)
 	}

diff --git a/avatar/avatar_test.go b/avatar/avatar_test.go
@@ -107,9 +107,10 @@ func TestAvatar_Routes(t *testing.T) {
 
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path == "/pic.png" {
-			w.Header().Set("Content-Type", "image/*")
+			// set wrong content type, in reality would be image/png based on the first bytes
+			w.Header().Set("Content-Type", "image/jpg")
 			w.Header().Set("Custom-Header", "xyz")
-			_, err := fmt.Fprint(w, "some picture bin data")
+			_, err := fmt.Fprint(w, "\x89PNG\x0D\x0A\x1A\x0A some picture bin data")
 			require.NoError(t, err)
 			return
 		}
@@ -154,16 +155,16 @@ func TestAvatar_Routes(t *testing.T) {
 		handler.ServeHTTP(rr, req)
 
 		assert.Equal(t, http.StatusOK, rr.Code)
-		assert.Equal(t, []string{"image/*"}, rr.Header()["Content-Type"])
-		assert.Equal(t, []string{"21"}, rr.Header()["Content-Length"])
+		assert.Equal(t, []string{"image/png"}, rr.Header()["Content-Type"])
+		assert.Equal(t, []string{"30"}, rr.Header()["Content-Length"])
 		assert.Equal(t, []string(nil), rr.Header()["Custom-Header"], "strip all custom headers")
 		assert.NotNil(t, rr.Header()["Etag"])
 
 		bb := bytes.Buffer{}
 		sz, err := io.Copy(&bb, rr.Body)
 		assert.NoError(t, err)
-		assert.Equal(t, int64(21), sz)
-		assert.Equal(t, "some picture bin data", bb.String())
+		assert.Equal(t, int64(30), sz)
+		assert.Equal(t, "\x89PNG\x0D\x0A\x1A\x0A some picture bin data", bb.String())
 	}
 
 	{

diff --git a/v2/avatar/avatar.go b/v2/avatar/avatar.go
@@ -23,6 +23,9 @@ import (
 	"github.com/go-pkgz/auth/v2/token"
 )
 
+// http.sniffLen is 512 bytes which is how much we need to read to detect content type
+const sniffLen = 512
+
 // Proxy provides http handler for avatars from avatar.Store
 // On user login token will call Put and it will retrieve and save picture locally.
 type Proxy struct {
@@ -100,7 +103,6 @@ func (p *Proxy) load(url string, client *http.Client) (rc io.ReadCloser, err err
 
 // Handler returns token routes for given provider
 func (p *Proxy) Handler(w http.ResponseWriter, r *http.Request) {
-
 	if r.Method != "GET" {
 		w.WriteHeader(http.StatusMethodNotAllowed)
 	}
@@ -136,9 +138,21 @@ func (p *Proxy) Handler(w http.ResponseWriter, r *http.Request) {
 		}
 	}()
 
-	w.Header().Set("Content-Type", "image/*")
+	buf := make([]byte, sniffLen)
+	n, err := avReader.Read(buf)
+	if err != nil && err != io.EOF {
+		p.Logf("[WARN] can't read from avatar reader for %s, %s", avatarID, err)
+		rest.SendErrorJSON(w, r, p.L, http.StatusInternalServerError, err, "can't read avatar")
+		return
+	}
 	w.Header().Set("Content-Length", strconv.Itoa(size))
+	w.Header().Set("Content-Type", http.DetectContentType(buf))
 	w.WriteHeader(http.StatusOK)
+	if _, err = w.Write(buf[:n]); err != nil {
+		p.Logf("[WARN] can't write response to %s, %s", r.RemoteAddr, err)
+		return
+	}
+	// write the rest of response size if it's bigger than 512 bytes, or nothing as EOF would be sent right away then
 	if _, err = io.Copy(w, avReader); err != nil {
 		p.Logf("[WARN] can't send response to %s, %s", r.RemoteAddr, err)
 	}

diff --git a/v2/avatar/avatar_test.go b/v2/avatar/avatar_test.go
@@ -107,9 +107,10 @@ func TestAvatar_Routes(t *testing.T) {
 
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path == "/pic.png" {
-			w.Header().Set("Content-Type", "image/*")
+			// set wrong content type, in reality would be image/png based on the content of the file
+			w.Header().Set("Content-Type", "image/jpg")
 			w.Header().Set("Custom-Header", "xyz")
-			_, err := fmt.Fprint(w, "some picture bin data")
+			_, err := fmt.Fprint(w, "\x89PNG\x0D\x0A\x1A\x0A some picture bin data")
 			require.NoError(t, err)
 			return
 		}
@@ -154,16 +155,16 @@ func TestAvatar_Routes(t *testing.T) {
 		handler.ServeHTTP(rr, req)
 
 		assert.Equal(t, http.StatusOK, rr.Code)
-		assert.Equal(t, []string{"image/*"}, rr.Header()["Content-Type"])
-		assert.Equal(t, []string{"21"}, rr.Header()["Content-Length"])
+		assert.Equal(t, []string{"image/png"}, rr.Header()["Content-Type"])
+		assert.Equal(t, []string{"30"}, rr.Header()["Content-Length"])
 		assert.Equal(t, []string(nil), rr.Header()["Custom-Header"], "strip all custom headers")
 		assert.NotNil(t, rr.Header()["Etag"])
 
 		bb := bytes.Buffer{}
 		sz, err := io.Copy(&bb, rr.Body)
 		assert.NoError(t, err)
-		assert.Equal(t, int64(21), sz)
-		assert.Equal(t, "some picture bin data", bb.String())
+		assert.Equal(t, int64(30), sz)
+		assert.Equal(t, "\x89PNG\x0D\x0A\x1A\x0A some picture bin data", bb.String())
 	}
 
 	{